TM 5-3895-382-24 Problem 10 Engine knock occurs. Probable Cause 1. The main bearing is damaged. Inspect  the  main  bearings  and  the  bearing  surface  of the crankshaft.  Replace damaged parts. 2. The crankshaft is damaged. Replace the crankshaft.  Clean the engine thoroughly. Problem 11 The  rocker  arm  has  insufficient  movement  and  the  valve lash exceeds the specification. Probable Cause 1. Lubrication of internal engine components is inadequate. Check lubrication of the valves.  There must be a strong flow of oil at engine high rpm, but only a small flow at low rpm.  Oil passages must be clean. 2. Rocker arm parts are worn. If  there  is  too  much  wear,  install  new  parts  or  rocker arms.  Adjust the valve lash. 3. The end of the valve stem is worn. Install new valves.  Adjust the valve lash. 4. The valve lash exceeds the specification. Measure the valve lash.  Adjust the valve lash. 5. The pushrods are worn. If there is too much wear, install new pushrods.  Adjust the valve lash. 6. The valve lifters are worn. If   there   is   too   much   wear,   install   new   valve   lifters. Adjust the valve lash. 7. The lobes of the camshaft are worn. Measure  the  valve  lash.    Check  for  free  movement  of the valves.  Check for bent valve systems.  Check for wear   on   the   valve   lifters.      Replace   defective   parts. Adjust the valve lash. 8. The   bolts   and   the   nuts   that   hold   the   rocker   arm assembly are loose. 9. Tighten the bolts and the nuts. Problem 12 The valve is loose. Probable Cause 1. The spring lock for the valve is broken. Replace  the  spring  lock.    Broken  locks  can  cause  the valve  to  slide  into  the  cylinder.    Major  engine  damage can result. 2. The valve springs are broken or damaged. Install new valve springs. Problem 13 Oil condenses at the exhaust Probable Cause 1. The valve compartment contains too much oil. Look at both ends of the rocker arm shaft.  Be sure that a plug is installed in each end. 2. The valve guides are worn. Install new valve guides.  Recondition the cylinder head. 3. The piston rings are worn. 4. Replace the piston rings. Problem 14 The valve lash is less than the specification. Probable Cause 1. The valve seat or the face of the valve is worn. Recondition the cylinder head.  Adjust the valve lash. 6-43